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i second what Broaner said. i still believe its a trans problem thats killing your thrust bearings
 

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3 footin' through life
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Too much pressure applied to the TC from the valve body will cause ballooned TCs at higher RPMs. My guess would be to change that at this point. What else is there to blame? A bent crank maybe?

Sent from my SM-N950U using Tapatalk
 

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Just finished reading every word. Conventional and mild machining on rebuild after an overspeed. Tolerances back from the machine shop the first time too tight. Loosened up. Two cranks. Three thrust bearings. Had the valve body checked and mic'd out the TC and no apparent overpressure damage detectable exterior to the converter.

Gotta be the transmission.

Found this ... a discussion of thrust bearing failure subsequent to engine rebuilds:

thrust bearing wear | Grumpys Performance Garage

Note the technical discussion relevant to the converter and the failure modes, where it addresses energy transfer due to clutch weakness into forward thrust.
 

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That was really a great read. After assimilating all that info it could be related to the TC, crank to bearing surface finish, or improper installation and seating of bearings. The devil really is in the details.
 

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I can't remember if BZ2500 said it but someone here was talking about having a crank ground for more clearance. If it was done improperly that could be it also. The fix could be as simple as a new crank and bearings.
 

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Yeah, but the OP double checked all the clearances out of an abundance of caution both cranks. That's how he caught the tight piston and ring fits the first time around. It's gotta be something he couldn't detect with a mic or a dial indicator. And since he did have the valve body evaluated, it's gotta be something inside the converter or in the interface between the core and the converter.
 

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Discussion Starter #369
That was a great read! More and more pushing me towards the trans. I never sent in the convertor for testing because I simply couldn’t mail it and I coulnt take it with me in the plane unless I cut it open. A while back when I spoke to Dave Goerend he mentioned many things listed in that article. That spline lock condition was very alarming to me, Dave said it could put 1000 lbs of pressure on the crank. From the pics I posted with the bearing all bent like that I have to be dealing with some crazy pressure.

Also I’ve been using Garmons fatshaft convertor and input. Worked well for me for a few years but after that over rev who knows what happed in that convertor. Funny thing is that after the rebuild it worked fine I really count tell if there was an issue with it.

The plan now is repair crank, make sure thrust surface is perfect and polished like a mirror. Trans is going all stock. Stock input, stock convertor and valve body with a shift kit.

Sell the truck and get rid of this headache..
 

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Discussion Starter #370
Wanted to update this thread for a while but thought it was closed..

Guess what! New owner of the truck had the thrust break a few months after purchasing.. This time everything was put back to stock. Stock convertor, different valve body with just a trans go kit, engine was put back to the original saddle jet oiling with 03 style pistons..

How in the hell is this thrust breaking....
 

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The only way for repeated failure is it not being set up properly.
 

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Discussion Starter #372
What not being set up right? clearances have been gone through over and over..
 

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3 footin' through life
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Wild **** dude. At that point I think I would just totally give up on that entire engine and transmission. :) At least in a manual you know where the thrust pressure is coming from. ;)
 

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Discussion Starter #374
Wild **** dude. At that point I think I would just totally give up on that entire engine and transmission. :) At least in a manual you know where the thrust pressure is coming from. ;)
It just horrible. I probably win the award for worst luck after a rebuild. We are getting rid of that engine and trans.. putting in the 6.7 I brought down from the states and I’m putting a different trans thats gonna get a stock rebuild. Even using a different adapter and flex plate. So absolutely nothing from the old setup is being used.

This time the thrust was ground down. Only a sliver of it was left behind. I’m thinking must be the thrust surface on the crank is not polished enough And it slings the oil away.
 

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Good choice. Just be done with that one. Who knows why but solution is simple enough. Currency is overrated anyway. haha
 
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Well one has to feel for Belize2500. The amount of time and money he put into this crazy engine issue.
I hope he is doing well. 👍


Something had/has to be forcing the crankshaft forward to wear out the thrust bearing.
Since the thrust bearing is wearing out so quickly, there has to be significant force.

I can't think of anything on the front of the engine that could be jamming the crank forward.
Crank geartrain, ATI damper, belt drive, etc.

So it must be something at the back pushing the crank forward after the engine is bolted to the trans.

With the engine fully assembled but not bolted to the trans, you should still be able to push the crank back and forth to confirm crank end play.
I have never tried this on any engine. It would take some leverage with a pry bar or something similar but this would eliminate an engine assembly issue.

With the engine fully bolted to transmission but the tq converter NOT bolted to the flex plate, you should still be able to push the crank back and forth to confirm crank end play, that the crank is not being forced forward.
This would eliminate something not correct with the transmission adapter plate, engine to trans alignment, etc.

If that was still ok, then the tq converter gets bolted to the flexplate.
Now I'm not sure how you would pry the crank back and forth.
I guess iff the oil pan was not installed at this point, or even prior, you would be able to pry the crank back and forth to confirm crank endplay.

Hopefully at one of these steps, you would find something in the engine to transmission relationship jamming the crank forward.

It's been a while since I've had a Cummins apart. The last one over 5 years ago. We set the crank in the block, torqued it down, Spun it, quickly checked endplay 90degrees of crank rotation at a time and called it good.
Spent 2 minutes on endplay and the thrust bearing without even thinking about it.
I also use plastigauge for crank bearing clearances.


Just my thoughts, of course after the fact...
 
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